1. Technical Field
The invention disclosed broadly relates to electrical computers and data processing systems and more particularly relates to data processing systems and methods for editing structured document text.
2. Background Art
Modern word processing and text editing programs employ structured document architecture to provide greater control and flexibility in the displayed and printed appearance of documents prepared with the programs. Structured document architecture is described, for example, in the below referenced U.S. patent application by Bennett, et al. A structured document can be prepared in accordance with the Standardized General Markup Language, such as is described in the International Standards Organization, Standard 8879-1986. A data stream of text marked up in accordance with the Standardized General Markup Language, will have its text divided into elements consisting of a begin tag and its content and terminated by an end tag, when necessary. Within a WYSIWYG (what you see is what you get) editor, text is displayed to the user as it will appear when it is printed, even though its structure is defined by the begin tags and end tags for each element of text. Formatting of the elements within a structured document is done when the document is displayed to the user. Those elements which fall into the category of commonly used elements include paragraphs, simple lists, ordered lists, bulleted lists, list items, headings, and document titles. A hierarchical structure can be attributed to these various elements, such as assigning the title element as having the highest level in a hierarchy, assigning a chapter heading as having a next highest level in the hierarchy, and assigning a paragraph element as having a third highest level in an example structured document hierarchy.
The appearance of a structured document text when it is displayed on a display screen or when it is printed in hard copy, should be in its WYSIWYG (What You See Is What You Get) form. In the prior art, editors and word processors have provided some specifications for the appearance of the WYSIWYG presentation of the text, for example the setting of margins, the specification of tabs, and the specification of fonts. Typically, prior art editors and word processors would impose the margin settings for the entire document and the font style for the entire document. Editors and word processors might provide for the insertion of bold face tags for designated portions of the text, however the association of the bold face tag with the text would be immutably fixed with respect to the particular designated text. An underline emphasis in the prior art was conducted in the same way, where a beginning mark and an ending mark for the underlined portion of the text was embedded into the text. If the text were moved or copied to another portion of the document, the bold face or underline emphasis would remain associated with the text, despite any intention on the part of the user to avoid carrying along the particular form of emphasis.
In the prior art there have been some examples of structured document architecture applied to editors and word processors. In such prior art editors and word processors, attempts have been made to control, to a limited degree, the WYSIWYG appearance of the text when it is displayed on a display screen or printed in hard copy. Typically, overall characteristics for a section of the text might have specified the margins, font and perhaps some forms of emphasis such as bold face and italic. If the user writes a sentence which he intends to be all in italic, with a first portion in italic, a middle portion combined bold face and italic, and an end portion being only italic, the prior art editors and word processors would consider this sentence to be composed of three separate alphanumeric strings, with the first string being separately specified as italic, the middle string being separately specified as both bold face and italic, and the third string being separately specified as italic. If the user, at a later stage in the editing session, wants to copy the middle section of the sentence to another portion of the document, when the user copies that section to another part of that document, it will appear in the new portion of the document in both the combined italic and bold face appearance. If the user had intended that the copied middle portion of the sentence no longer have the italicized characteristic but only the bold face characteristic in its copied new location, he would have failed in achieving his intentions since the prior art editor would have continued to provide the combined italicized and bold face appearance for the copied portion, notwithstanding the fact that it occupied a separate, non-italicized portion of the document. This occurred in the prior art because the prior art editors and word processors would not maintain the appearance characteristics of a document element on an individualized hierarchical level. This is just one example of many failings of the prior art in not reflecting the user's intention in editing structured documents.